The invention relates to a gas-insulated multi-phase line made up of sections, each of which is formed by metal cladding filled with a dielectric gas under pressure and containing the phase conductors. This type of line must be capable of receiving current-measuring instruments or the like, such as a current transformer. In order to install a multi-phase transformer, it is necessary for the windings that form the secondary of the transformer to be disposed around respective ones of the phase conductors, these conductors being disposed in the same tubular metal cladding filled with an insulation gas under a pressure of a few bars. At present, the windings are mounted inside the metal enclosure of a connection module between two adjacent line sections and they are thus immersed in the dielectric insulation gas. That configuration of windings requires the electrical wires of the secondary to be passed through the metal enclosure of the module via gastight feedthroughs, which is particularly costly to achieve. Since the windings are disposed inside the enclosure, the internal volume of the module must be designed accordingly, which poses problems of resistance to pressure for the enclosure and for the gastight feedthroughs.
An object of the invention is to mitigate the above-mentioned drawbacks.
To this end, the invention provides a gas-insulated multi-phase line made up of sections, each of which is formed by metal cladding filled with a dielectric gas under pressure and containing at least three phase conductors disposed in a triangle configuration, wherein two adjacent sections are connected together via a connection module whose metal cladding is locally made up of a plurality of tubular portions, each of which is filled with dielectric gas and has a single phase conductor passing through it constituting a passive electrical connection.
With this local structure for the line, it is possible to mount the windings of the secondary of a current transformer in air around the tubular portions, which contributes to reducing significantly the manufacturing cost and the maintenance cost of the current transformer.
The invention also provides a connection module for such a gas-insulated line, as well as a method of assembling such a connection module so that it can receive the secondary windings of a current transformer.